As the year comes to an end, Poplar faces unprecedented and relentless wintry conditions, which pose a challenge to the occupants of Nonnatus House and the community at large.

As the Big Freeze of 1963 continues, Nonnatus House welcomes their newest midwife, while contending with the effects of the weather.

As Lucille settles into her duties, she faces prejudice from a patient's mother, while Sister Winifred opens her mothercraft classes up to fathers, and the Turners meet their new au pair.

A patient of Phyllis' receives a devastating diagnosis, Fred and Violet organise a beauty pageant, Magda discloses a secret, and Trixie makes a tough decision.

Trixie battles her demons and Sister Monica Joan faces losing her eyesight, while Sister Julienne assists a childless Pakistani woman after her husband is pressured to marry a second wife.

The fear of a potential smallpox outbreak grips Poplar, Lucille helps a woman with a phobia of childbirth, and the Buckles organize a charity picnic.

A recently widowed expectant mother faces hardship, Valerie and Lucille's teenage health class is met with opposition, and Sister Monica Joan prepares for her cataract surgery.

The Turners attempt to improve the life of a young man from a remand home, Lucille finds unexpected friendship, while Nonnatus House is filled with worry for Barbara.

A nearby maternity home closes, bringing new patients to Nonnatus, while Tom deals with his grief and Sister Monica Joan is given a surprise.